1. Field
The present disclosure relates generally to generating stereoscopic images for computer animation, and more specifically to using window objects to avoid clipping a computer-generated object near the edge of an image.
2. Related Art
Cinematographic-quality computer animation has evolved to produce increasingly realistic and engaging visual effects. One way that this is accomplished is through the use of stereoscopic filming techniques that simulate human binocular vision by presenting slightly different viewpoints of a scene to a viewer's left and right eye. This technique, also known colloquially as “3D,” can be used to enhance the illusion of depth perception and make objects in a computer-generated scene appear to extend outward from a two-dimensional screen.
In normal human binocular vision, each eye views the world from a slightly different perspective. The difference in the view from each eye, also called parallax, is caused, in part, by the spatial separation between the eyes. In general, the amount of parallax is increased for objects that are closer to the viewer as compared to objects that are further from the viewer. The brain is able to combine the different views from each eye and use the parallax between views to perceive the relative depth of real-world objects.
Computer-animation stereoscopic filming techniques take advantage of the brain's ability to judge depth through parallax by presenting separate images to each eye. Each image depicts a computer-generated object from a slightly different viewpoint. The distance between the left and right images displayed on a screen (parallax) indicates the relative depth of the displayed computer-generated object. Parallax can be positive or negative depending on whether the computer-generated object appears to be behind the screen (positive parallax) or if it appears to be in front of the screen (negative parallax).
In general, stereoscopic filming techniques use parallax to take advantage of the brain's ability to judge depth based on differences between the visual input from left and right eyes. However, if an object depicted in a stereoscopically filmed scene is clipped by the edge of the image or screen, the viewer may be presented with a visual paradox. As previously explained, an object that is displayed with negative parallax will appear to protrude from the screen plane. However, if a portion of the object falls outside of the display screen area, the object will appear to be hidden or masked behind the edge of the screen, which is behind the protruding object. This effect may be visually distracting, detracts from stereo effect of the displayed image, and is generally undesirable.
What is needed is a technique for preventing or minimizing the effect of this visual paradox in stereoscopically filmed images.